Polymer coloration

ABSTRACT

The invention concerns the coloration of hot melt polymer by direct injection of a dye into a stream of the polymer after or in a late stage of polymerisation e.g., before feed to a spinning machine. Separate pressure-balanced continuous flow metering pumps respectively feed melted undyed polymer and melted concentratedcolour-dyed polymer to a mixer and the pumps are controlled to run in a speed relationship adjustable for colour and colour constancy. A three stage gear pump is preferably used for the colour-dyed polymer, undyed polymer being bled to the second inlet of this pump for premixing.

United States Patent [1 1 Hoyle et a1.

POLYMER COLORATION Inventors: John Hoyle; Thomas Reuben Griffin,

Kegworth, Near Derby, England Assignee: Slack & Parr Limited, Kegworth,

England Filed: July 8, 1971 App1. No.: 160,813

Foreign Application Priority Data July 8, 1970 Great Britain 33,247/70 U.S. Cl 259/4, 137/566, 137/567 Int. Cl. B011 13/10, B011 15/04, B011 5/14 Field 01' Search 259/4, 7, 8, 18, 259/21, 22, 23, 24, 60, 154; 137/566, 567, 604; 418/196 References Cited UNITED STATES PATENTS 8/1958 Franklin et a1. 259/8 12/1960 Hawkinson et a1. 137/566 X [11] 3,754,735 1451 Aug. 28, 1973 3,171,721 3/1965 Stratheam et a1. 259/8 X 3,023,764 3/1962 Dooley et a1. [37/566 X 3,272,141 9/1966 Curry et a1 418/196 X 3,000,053 9/1961 Hart 137/567 X Primary Examiner-John Petrakes Assistant Examiner-Philip R. Coe Attorney-Irvin S. Thompson and Robert .1. Patch 1 5 7] ABSTRACT and the pumps are controlled to run in a speed relationship adjustable for colour and colour constancy. A three stage gear pump is preferably used for the colour-dyed polymer, undyed polymer being bled to the second inlet of this pump for premixing.

3 Claims, 2 Drawing Figures POLYMER COLORATION This invention relates to the coloration of hot melt.

polymer and has for its object to provide an improved method and improved apparatus for the direct injection of a dye into a stream of the: polymer either after. polymerisation or in a late stage of polymerisation. It is of particular advantage in the coloration of a hot melt polymer immediately prior to the latter being fed to a.

spinning machine.

According to the invention, apparatus for the coloration of a hot melt polymer comprises separate. pressure-balanced continuous-flow metering pumps which respectively feed melted undyed polymer and melted concentrated-colour-dyed polymer to a mixer, the pumps being controlled to run in.a speed relationship which is adjustable to determine the colour shade and maintainable for constancy of colour shade.

The actual speed may be controlled to vary the inputs and therefore also the common output of the mixer according to the requirements of a spinning, machine or other forming device fed from themixer.

Preferably a three-stage gear pump is employed for the colour-dyed polymer, which polymer is fed to one pump inlet, undyed polymer beingbledifrom'the mixed input line. to the other pump inlet of the three-stage gear pump for premixingtherein.

For the pressure feed. of melted polymer'to thefcontinuous flow metering pumps to establish pressure. balance therein, heated screw extrudersmay beused, or melting pots or conduits coupled to booster gear pumps, the extrudersor melting. potsbeingfedlfrom hoppers, one for colouredchip'polymer and the. other for undyed chip polymer. Each of. the two pressure feeds is, in the use of theapparatus, adjustedto approximate to the inlet mixer pressure so that inlet andoutlet pressures of both meteringpumps are alliapproximately equal. This ensures'accurate meteringand' coloration.

The mixer, in which intimate mixing of the'dyeinto the polymer is achieved, may beoffthe rotary. type having a disc-type rotor which provides a mixing, action which is a combination of shearing anddividing.

The invention also provides a method of colouring a hot melt polymer comprising the steps of melting. undyed polymer chip and feeding it under pressure to a main continuous-flow metering pump discharging into a mixer, separately melting concentrated'colour-dyed polymer chip and feeding it under. pressure to a continuous flow colour metering pump discharginginto said mixer, adjusting the speed relationship ofthe pumpsfor colour shade and maintaining that speedrelationship for constancy of colour shade.

Two forms of apparatus for'the coloration of ahot melt polymer, representing embodimentsof the invention, and illustrative of the method. of. the invention,.

will now be described by way of example, and.with.reference to the accompanyingdrawings, in which:

FIG. 1 illustrates the firstof the two forms of apparatus,

FIG. 2 illustrates the second form of apparatus.

In one of the forms, concentrated-colour-dyed.polymer chip contained in a hopper l is fed into a screw extruder 2 in which the chip is melted. The output fromthe extruder feeds into one port/3 of a three-gear pump 4-. Undyed polymer chip is contained ina second hopinto the inletport 7 of a two-gear pump 8, the outlet from which is fed via a line 9 ma rotating disc-type mixer 10. In the line 9 between pump 8 and mixer 10 a tapping 11 is taken off and led into the second inlet 12. of the three-gear pump 4. A measure of premix is therefore obtained in the three-gear pump 4. Moreover, the introduction of undyed polymer into the pump 4 serves to reduce abrasive wear when the concentrated colour dye polymer is abrasive in nature.

The combined output of the three-gear pump is also fed over a line 13 into the mixer 10 where the final complete mixing with the main flow of polymer-take place. The mixer 10 delivers into amanifold l4 supplying the individual meteringpumps feedingspinnerets of a spinning machine.

The speed of the two-gear mixer feed pump 8'is variable to meet the demands of the spinning pumps. It may to this end be regulated to maintain aconstant pressure head in the manifold 14. Control viaa coupling 15 can be effected. through the use of a pressure sensing transducer 16 located in the feed line 17 to the manifold 14 feeding the spinning pumps.

In order to. maintain a constant proportion of dye to the main flow, the drive to the three-gear pump 4, whilst'providing thefacility for speed change independentiof the main two-gear pump 8,.to accommodate differing-dye concentrations, is controlled-by coupling l8 to run in. a constant speed relationshipto the main two-gear pump 8..

The screw extruder 2. feeding concentrated colour dyed polymer to the three-gear pump 4 may also have a speed: control interlocked in. a coupling 19 with the three-gearpump'4 to maintain a close. pressure balance between both inlets 3- and. 12" of this pump. Alternatively, the pressure/throughput characteristics of the extruder 2' may be designed to obviate the need for such interlock.

In the variantarrangement shown in FIG. 2 there is provided,.instead of the screw extruders 2 and-6, separate melting pots 20 and 21 or equivalent feeding booster gear pumps 22 and 23. Each of these pumps 22, 23 fulfils the function ofa screw extruder as a pressure generating device and maintains a pressure balance across the two inlets 3 and 12 of the three-gear pump 4 as in the previous arrangement.

In both the arrangements described all the pumps and the mixer, also the screw extruders where used, are contained within temperature controlled'zones, and the temperature is maintained above the melt temperature of the polymer.

We claim:

1. A method of producing coloured hot melt polymer which comprises the steps of:

a. melting undyed polymer chip and feeding it under pressure to a first continuous flow metering pumpthe discharge outlet of which is connected by a main line to a mixer and by a branch line to an inlet of a. second continuous'flow metering pump,

b. separately melting concentrated colour-dyed polymer chip and feeding it under pressure to another inlet of the second continuous flow metering pump, the discharge outlet of said second pump being connected to the mixer, and

c. providing means downstream of the mixer controlling the rates of operation of the pumps in dependence on the pressure of the coloured hot melt polymer passing along a feed line issuing from the mixer.

2. Apparatus for producing coloured hot melt polymer which includes:

1. a first continuous flow metering pump having an inlet and a discharge outlet,

2. a second continuous flow metering pump having a pair of inlets and a discharge outlet,

3. means for melting undyed polymer chip and means for feeding said hot melt polymer under pressure to the inlet of the first continuous flow metering 4. separate means for melting concentrated colourdyed polymer chip and means for feeding said dyed hot melt polymer under pressure to one of the inlets of the second continuous flow metering pump,

5. a mixer,

6. a main line extending from the discharge outlet of the first continuous flow metering pump to the mixer,

7. a branch line extending from the main line to the other inlet of the second continuous flow metering 8. a line extending from the discharge outlet of the second continuous flow metering pump to the mixer,

9. a feed line issuing from the mixer and l0. means in said feed line for sensing the pressure of hot melt polymer therein and for controlling the rates of operation of the pumps in dependence on said pressure.

3. Apparatus according to claim 2, wherein the means for feeding hot melt polymer to each continuous flow metering pump comprises a respective screw extrude r. 

1. A method of producing coloured hot melt polymer which comprises the steps of: a. melting undyed polymer chip and feeding it under pressure to a first continuous flow metering pump the discharge outlet of which is connected by a main line to a mixer and by a branch line to an inlet of a second continuous flow metering pump, b. separately melting concentrated colour-dyed polymer chip and feeding it under pressure to another inlet of the second continuous flow metering pump, the discharge outlet of said second pump being connected to the mixer, and c. providing means downstream of the mixer controlling the rates of operation of the pumps in dependence on the pressure of the coloured hot melt polymer passing along a feed line issuing from the mixer.
 2. ApparatuS for producing coloured hot melt polymer which includes:
 2. a second continuous flow metering pump having a pair of inlets and a discharge outlet,
 3. means for melting undyed polymer chip and means for feeding said hot melt polymer under pressure to the inlet of the first continuous flow metering pump,
 3. Apparatus according to claim 2, wherein the means for feeding hot melt polymer to each continuous flow metering pump comprises a respective screw extruder.
 4. separate means for melting concentrated colour-dyed polymer chip and means for feeding said dyed hot melt polymer under pressure to one of the inlets of the second continuous flow metering pump,
 5. a mixer,
 6. a main line extending from the discharge outlet of the first continuous flow metering pump to the mixer,
 7. a branch line extending from the main line to the other inlet of the second continuous flow metering pump,
 8. a line extending from the discharge outlet of the second continuous flow metering pump to the mixer,
 9. a feed line issuing from the mixer and
 10. means in said feed line for sensing the pressure of hot melt polymer therein and for controlling the rates of operation of the pumps in dependence on said pressure. 